The present invention relates to the art of brake adjusting mechanism and, more particularly, to those brake slack adjusting mechanisms commonly used on large vehicles such as dump trucks and the like and where such mechanisms are externally mounted to the axle of the truck and operate shafts to take up the slack in the brake mechanisms.
A brake slack adjusting mechanism commonly in use today and to which the improvements of the present invention apply is shown in FIG. 1 of the drawings. The conventional brake slack adjuster 10 includes a worm drive and spline drive adjuster housing 11 which terminates in an anchor arm 12. In conventional use, the anchor arm 12 is secured to the axle of the vehicle of the related components to secure the brake slack adjuster 10 in place.
The adjuster housing 11 includes therein a worm drive (not shown) which drives a brake adjuster spline 13. The brake adjuster spline 13, in turn, drives a spline shaft (not shown) which is interconnected to the vehicle braking mechanism to expand or adjust the brakes as the adjuster spline 13 is rotated.
The brake slack adjuster 10 includes, extending from the worm drive (not shown) within the adjuster housing 11, a worm drive adjusting bolt 14. The worm drive adjusting bolt 14 terminates in a six sided adjusting bolt head 15. Rotation of the adjusting bolt head 15 will drive the worm drive (not shown) which, in turn, drives the brake adjuster spline 13 to thus apply a torque to the spline shaft (not shown) to ultimately adjust the brakes.
The conventional brake slack adjuster 10 has, extending from the adjuster housing 11 and in axial alignment with the worm drive adjusting bolt 14, a socket lock boss 16. Journaled within and extending from the socket lock boss 16 is a spring loaded adjusting bolt head socket lock 17. The adjusting bolt head socket lock 17 includes, on the outer circumference thereof, a key 18 which cooperates with a slot 19 in the socket lock boss 16 to prevent the adjusting bolt head socket lock 17 from turning.
The spring loaded adjusting bolt head socket lock 17 operates in a manner such that, when a socket wrench or other suitable wrench is placed upon the adjusting bolt head 15 and pressed against the spring pressure of the spring loaded adjusting bolt head socket lock 17, the adjusting bolt head socket lock 17 will move inwardly into the socket lock boss 16 and thus move free and clear from its locking relationship with the adjusting bolt head 15 thus permitting the adjusting bolt head 15 to be rotated to adjust the slack of the brakes. Upon release of the pressure upon the spring loaded adjusting bolt head socket lock 17, the bolt head socket lock 17 will move outwardly and into engagement with the adjusting bolt head 15 whereupon the internal socket 20 of the adjusting bolt head socket lock 17, which is of configuration complementary to that of the adjusting bolt head 15, will move into locking engagement with the adjusting bolt head 15 and thus prevent the adjusting bolt head 15 from turning to prevent misadjustment of the vehicle brakes.
The conventional brake slack adjusting mechanisms as above described perform reasonably satisfactory in their function when new. However, the operation of the vehicle is constantly applying a torque back through the spline shaft (not shown) to the brake adjuster spline 13 and through the worm drive (not shown) to cause constant flexing or torquing of the adjusting bolt head 15 against the adjusting bolt head socket lock 17. These vehicles such as dump trucks and the like operate in extremely corrosive atmospheres and abrasive atmospheres due to the dust, dirt and other wear inducing road particles. As a result, the constant flexing or torquing of the adjusting bolt head 15 within the bolt head socket lock 17, working in conjunction with the corrosive and abrasive atmosphere in which these vehicles operate, results in very quick and premature destruction of the surfaces of the adjusting bolt head 15 and adjusting bolt head socket lock 17 with the consequent failure of the mechanism in that the adjusting bolt head 15 will turn within the bolt head socket lock 17 thus permitting the adjustment of the braking mechanism to be lost.
The failure of the brake slack adjuster, by reason of the slippage between the adjusting bolt head 15 and bolt head socket lock 17, results in constant need to readjust the mechanism to properly adjust the brakes which is both costly from the point of view of lost manpower and vehicle usage. More importantly, the failure of the brake slack adjuster by these reasons sets forth a dangerous situation in the possibility of brake failure on the vehicle.